Method _appendUpdate

src/proxy/mailbox/store.js:316–320

(id, fields)

  }

  _appendUpdate(id, fields) {
    appendLine(this._messagesFile, { _op: 'update', id, fields });
    const existing = this._messages.get(id);
    if (existing) safeAssign(existing, fields);
  }

  _evictFromIndex(id) {
    const msg = this._messages.get(id);